Scalable Synthesis of Exfoliated Organometal Halide Perovskite Nanocrystals by Ligand-Assisted Ball Milling

The scalable synthesis of colloidal organohalide perovskite nanocrystals is essential because of increasing demands for their use in many applications such as photovoltaic and light-emitting devices. However, only subgram quantities of perovskite nanocrystals were produced in the typical precipitation synthesis involving excess amounts of nonsolvent, limiting their high-yield production. In this contribution, ligand-assisted ball milling represents a substantial improvement in the scalability of high quality perovskite nanocrystals as well as the corresponding optoelectronic properties (e.g., PLQYs) by the synergetic effect of chemical fragmentation (i.e., ligand exfoliation) and mechanical shearing force. In particular, the formation of perovskite nanocrystals as well as exfoliated nanoplatelets was preferentially developed in the presence of ligands (n-octylamine or octadecylamine) that protect their surfaces after the reaction of solid precursors. This procedure is facile and robust enough to produce kilogram quantities of perovskite nanocrystals with a controlled crystal size, which allows their usage in practical applications.